Self-venting closure



Sept. 8, 1970 C. J. B. YOUNG. JR

SELF-VENTING CLOSURE Filed Aug. 6, 1968 IN VENTORf Charles J. BrookeYoungJr BY wuw R- lvU;

AGENT United States Patent 3,527,376 SELF-VENTING CLOSURE Charles J. Brooke Young, Jr., 512 Askin Road, St. Davids, Pa. 19087 Filed Aug. 6, 1968, Ser. No. 750,546 Int. Cl. B65d 51/16 U.S. Cl. 220-44 3 Claims ABSTRACT OF THE DISCLOSURE A self-venting closure includes a flexible diaphragm having a normally closed slit therein. The diaphragm is mounted in a cap, plug or body designed to provide a closure for a container. A protruding element is disposed in close proximity to the diaphragm to restrict the movement of the portion of the diaphragm having the slit. When pressure is exerted against the diaphragm, the portion of the diaphragm away from the central portion is flexed causing the slit to first open on the side of the diaphragm away from the protruding element.

Self-venting closures are well known. Generally, such a closure is used with a container involving the storage or shipment of certain materials or liquids which are capable of generating dangerous pressures within the container. In the absence of the self-venting closure, such pressures would tend to rupture the closure or cause the container to explode.

The high pressures within a container may be built up as a result of the types of materials or liquids stored, changes in temperature, storage in warm places, or exposure to sunlight. Excess pressures are also likely to build up when the container is subjected to agitation incident to handling or shipment.

Heretofore, a factor making the use of slits in flexible diaphragms impractical relates to stack pressure. Stack pressure refers to the weight of the material in a container or drum that exerts static and dynamic pressures on the diaphragm when the container is moved or stored in any position other than its normal upright manner. Conventional flexible diaphragms With slits have proven incapable of withstanding this stack pressure.

An example of one type of container wherein selfventing devices are needed and where stack pressure is a problem are drums storing paint or other high viscosity liquids. When excess pressure causes venting, slits of the conventional kind tend to become clogged as a result of materials and drying in the slit opening, which prevents the slit from opening at pressures which must be vented for safe shipment or storage.

It is an object of this invention to provide an improved and reliable self-venting closure device that can be used to package low or high viscosity materials without clogging or leaking at the vent, and that can be provided at an absolute minimum cost.

It is a further object of this invention to provide an improved self-venting closure device than can be adapted to withstand a wide range of stack pressures inside of a container.

It is still a further object of this invention to provide an improved self-venting closure device which will not tend to become clogged with continued use.

In accordance with the present invention, a closure assembly includes a main body for closing an opening in a container. A relatively thick flexible diaphragm having a centrally disposed slit therein is gripped about its periphery within an opening in the main body. A protruding element restricts the movement of the central portion of the diaphragm when pressure is exerted on the side of the diaphragm opposite the element. When pressure is exerted on the side of the diaphragm opposite the protruding element, the diaphragm will flex between the abutment and the gripped periphery of the diaphragm until the slit opens on the side of the diaphragm opposite the protruding element.

Other objects and advantages of the present invention will be apparent and suggest themselves to those skilled in the art from a reading of the following specification and claims, in conjunction with the accompanying drawing, in which:

FIG. 1 illustrates a closure assembly in a normal unventing condition, in accordance with the present invention;

FIG. 2 illustrates the closure assembly when pressure is exerted against the diaphragm to cause venting in accordance with the present invention;

FIG. 3 is a sectional view taken along lines 33 of FIG. 2;

FIG. 4 is a bottom view of the diaphragm taken along lines 4-4 of FIG. 1;

FIG. 5 is a bottom view of the diaphragm in its venting position taken along lines 55 of FIG. 2; and

FIG. 6 is a view of the diaphragm alone, in accordance with the present invention.

Referring to the drawing, a self-venting closure assembly 10 includes a main cap body 12 for threadedly engaging a container 13 to close an opening therein. The main body 12 includes a downwardly extending hollow cylindrical portion 14 forming a cavity therein. An aperture 16 in the top of the main body leads from the cavity 15 to the atmosphere. A protruding element 17 is centrally disposed within the inner wall surface or bore 18 of the cylindrical portion 14 and extends from the top of the main body into the cavity 15. The lower end of the hollow cylindrical portion 14 includes a concentric bore 19 of greater diameter than bore 18. An inclined shoulder 20 interconnects bore 18 with bore 19.

A flexible diaphragm of greater diameter than bore 19 is dimensioned to fit in tight sealing engagement with the same to close cavity 15. The bore 19 and shoulder 20 constitute means for inhibiting and restricting axial movement of the perimeter of the diaphragm 22 as a result of a build-up of pressure within the container. The bore 19 and shoulder 20, however, permit axial shift of the perimeter of the diaphragm.

The flexible diaphragm 22 may be circular in shape and have a predetermined thickness dependent upon the pressure to be vented from the container, as will be described. The diaphragm may be made of rubber, plastic or any one of various other materials which have the proper degree of flexibility and non-porosity.

The diaphragm 22 includes a centrally disposed slit 23 which is normally closed to provide good sealing and which is adapted to be opened when pressure within the container 13 exceeds a predetermined pressure, as will be described. The protruding element 17 extends in close proximity to the slit 23 and in some cases the element may actually contact the central portion of the top surface 25 of diaphragm 22.

The flexible diaphragm 22 also includes a circular cut 24 extending partly through the material of the diaphragm from the top surface 25 of the diaphragm. The cut may be normal to the plane of the diaphragm but in the present instance is angularly disposed relative to the top surface 25, as seen in FIGS. 1 and 6, and is designed to provide greater flexibility to the diaphragm during operation, as will be described.

When the pressure within the container 13 is normal, theposition of the diaphragm 22 with respect to the main body 12 and protruding element 17 is illustrated in FIG. 1 of the drawing. The diaphragm 22 is in an unflexed condition with the slit 23' firmly closed. The

3 circumferential edge of the diaphragm is in intimate c'ontact with the bore 19. Under the conditions illustrated in FIG. 1, the diaphragm 22 provides an effective seal between the interior of the container 13 and the atmosphere.

The position of the diaphragm 22 when the pressure within the container 13 exceeds a predetermined level is illustrated in FIGS. 2 and 3. When pressure is exerted against the bottom of the diaphragm 22, it tends to push the diaphragm upwardly. However, the bottom. surface 26 of the protruding element 17 in contacting the top surface 25 of the diaphragm 22 limits or prevents movement of the central portion of the diaphragm. Likewise, bore 19 of less diameter than the diaphragm and the inclined shoulder 20 constitute means for preventing upward movement of the perimeter of the diaphragm 22.

When the inner pressure within the container increases, the area of the diaphragm between the center and peripheral edge begins to flex upwardly in the manner illustrated in FIGS. 2, 3 and 5. The perimeter of the diaphragm assumes an axial shift. Slit 23 is opened, thereby permitting the pressure within the container to vent through the slit 23, past the projection 17 within cavity 15, and out through aperture 16. After the pressure has been relieved, the diaphragm 22 resumes its normal sealing position with the slit 23- being closed.

The circular cut 24 in the diaphragm 22 facilitates the flexing of the diaphragm at its outer edge. In effect, there is material of lesser wall thickness or depth in the diaphragm at the area of the cut, permitting this area to flex easier than uncut areas of the diaphragm. Because of this, the flexing at the cut enables the marginal edge portion 27 of the diaphragm to roll into seating engagement with the inclined shoulder 20 without substantial upward axial movement.

It has been found that in having the slit open in a direction opposite to that attained in prior art devices, the tendency to clog the slit because of the accumulation of particles of material during a previous venting is minimized. While it would appear that the open slit Within the container would tend to make the interior of the slit more susceptible to the accumulation of the material being vented, this is not the case. It is believed that the pressure operating against the sides of the slit during the venting keeps the slit clean. Also, the fact that this pressure is exerted in an area removed from the outside atmosphere containing oxygen for example aids in keeping the slit clean, since atmosphere does not react with the material during venting. Whatever the correct explanation may be, having the slit open in a direction other than norma makes possible the use of a relatively cheap self-venting device,'highly useful in dealing with either high or low viscosity fluids.

It should also be noted that with the protruding element 17 the relatively thick diaphragm makes the present invention especially useful for withstanding stack pressure as would be present if the container were placed upside down. -In this case, the protruding element 17 acts as a support for the diaphragm 22 and the relatively thick diaphragm serves as a rigid support for the material 4 within a container, especially high viscosity fluids, such as paint and the like.

The diaphragm may be designed to vent at certain predetermined pressures by proper selection of its size, thickness, and material, and size of the slit. The width of the abutment 17 and its distance from the top face of the diaphragm will also effect the operation of the device. Additionally, the radial pressure exerted on the diaphragm by bore 19 also efiects its operating characteristics. This makes it possible to design self-venting devices which will operate within certain ranges of pressures with the degree of reliability being such that no special final adjustments or special testing is required. Moreover, while the abutment is illustrated as being circular in cross-section, it is apparent that it may be rectangular or assume other cross-sectional shapes. Likewise, the length of the slot may be less than the diameter of the projection 17.

While there has been described what is at present considered to be the preferred embodiment of this invention, it will be obvious to those skilled in the art that various changes and modifications may be made therein without departing from the invention, and it is therefore aimed in the appended claims to cover all such changes and modifications as fall within the true spirit and scope of the invention.

I claim:

1. A self venting device for venting pressure from a container comprising a flexible element adapted to close an opening in said container and having a normally closed slit centrally disposed therein, said flexible element having an outside surface and an inside surface, a restricting element for restricting the movement of said flexible element, said restricting element being opposite said slit and disposed adjacent said outside surface of said flexible element, with pressure exceeding a predetermined level causing the slit portion of said flexible element to bear against said restricting element and the area of said flexible element away from said centrally disposed slit and the circumference thereof to be flexed thereby opening said slit first adjacent its inside surface so as to permit venting pressure from said container.

2. The invention as set forth in claim 1 wherein a cap body is provided for holding said flexible element.

3. The invention as set forth in claim 2 wherein said flexible element may include an area of reduced wall thickness somewhere between the restricting element and the circumference of the flexible element.

References Cited UNITED STATES PATENTS 1,865,764 7/1932 Keenan 215-56 2,162,455 6/1939 Hoge 215-56 3,416,696 12/1968 Alteneder 215-44 GEORGE T. HALL, Primary Examiner 

